Question

Clamorosus, sordidus and manus parvus are recessive traits located on chromosome 3 in the newly-discovered diploid species electio vigintiviginti. The genetic map of this region is cl-8-s-10-mp. If you performed a test-cross between a fully heterozygous female and a fully homozygous male and observed 500 progeny, how many phenotypic classes of progeny would be expected and in what numbers?

Answer 1

Answer:

cl----8 mu----s----10mu---mp

Distance between the genes (mu) = (%) of recombination frequency

Expected double crossover frequency = 8% x 10% = 0.008 or 0.8%

Explanation:

Class of gametes	Genotype	Frequency of reciprocal pair	Numbers	Frequency of each class	% of frequency = frequency * 1000
Parental	+ + +	100- all recombinant progeny	100%-(7.2%+9.2%+0.8%) = 82.8%	41.4%	41.4%*500 = 207
	cl s mp			41.4%	41.4%*500 = 207
SCO 1	+ s mp	RF in region 1 = SCO1 – DCO	SCO1 = 8% - 0.8% = 7.2%	3.6%	3.6% * 500 = 18
	cl + +			3.6%	3.6% * 500 = 18
SCO 2	+ + mp	RF in region 2 = SCO2 - DCO	SCO2 = 10% – 0.8% = 9.2%	4.6%	4.6% * 500 = 23
	cl s +			4.6%	4.6% * 500 = 23
DCO	+ s +	(RF in region 1) * (RF in region 2)	0.8%	0.4%	0.4% *500 = 2
	cl + mp			0.4%	0.4% *500 = 2